Chemical-analytical characterization and determination of 10-carboxymethyl-9-acridanone

The interferon inducer 10-carboxymethyl-9-acridanone, sodium salt (CMA) is chemically and physicochemically characterized. Furthermore, a fluorimetric method of specific determination of CMA is described. The use of this assay allows to determine the content of CMA both in aqueous solutions and also in serum with a sufficient accuracy.     

Kinetics of the transformation of dihydroambazone into ambazone

The oxidation of dihydroambazone (1) by oxygen is dependent on the pH-values of the solutions used. This transformation can be inhibited and excluded, respectively, by ascorbic acid using defined concentrations. The oxidation product ambazone (2) was determined spectroscopically at different pH-values. The rate of transformation in serum depends on the temperature and can also be inhibited with ascorbic acid.     

Antineoplastic activity and toxicity of dihydroambazone in comparison with ambazone (1,4-benzoquinone-guanylhydrazone-thiosemicarbazone)

Dihydroambazone 1, a soluble derivative of ambazone, was tested with an admixture of ascorbic acid (0.1, 0.25, or 0.5% in distilled water) for antineoplastic activity by different routes (i.p., p.o., s.c., i.v.) against leukemia P388, and by s.c. application against Lewis lung carcinoma on B6D2F1-mice. The results were compared with that of ambazone. 1 was as active as ambazone upon the per os d 1-4 schedule only. Ascorbic acid, added for stabilization of 1, had no significant influence on the results. Intravenously given 1 was of low activity. It proved to be toxic at 100 mg/kg body mass. The i.v. toxicity was estimated approximately on B6D2F1-mice (LD50: 150 mg/kg; LD100: 175 mg/kg; maximum tolerated dose (MTD): 100 mg/kg. A comparison between the MTD's of 1 and ambazone in mice and rats (Wistar) showed partly a somewhat better p.o. compatibility of 1. The expectation of a favourable i.v. applicable derivative from the otherwise in water nearly insoluble ambazone could not be realized.     

氯苄律定的结构表征

目的研究氯苄律定的结构与晶型。方法采用卡氏水分滴定法, 傅立叶变换红外光谱法, 热分析, 单晶和粉末X射线衍射法对氯苄律定的结构及晶型进行了研究。结果氯苄律定及其非对映异构体可用不同的熔点来区分。氯苄律定晶型A为三斜晶系，空间群为P-1, 每个晶胞中有两个互为镜象的分子，为一水合物。并对氯苄律定的两种晶型进行了鉴定。结论对氯苄律定的结构及晶型进行的研究对于其临床研究及重结晶工艺的选择均是十分有用的。     

Low-molecular-weight heparins: differential characterization/physical characterization

Low-molecular-weight heparins (LMWHs), derived from unfractionated heparin (UFH) through different depolymerization processes, have advantages with respect to the parent heparin in terms of pharmacokinetics, convenience of administration, and reduced side effects. Each LMWH can be considered as an independent drug with its own activity profile, placing significance on their biophysical characterization, which will also enable a better understanding of their structure-function relationship. Several chemical and physical methods, some involving sample modification, are now available and are reviewed.     

Solid-state characterization of nevirapine

The purpose of this investigation is to characterize nevirapine from commercial samples and samples crystallized from different solvents under various conditions. The solid-state behavior of nevirapine samples was investigated using a variety of complementary techniques such as microscopy (optical, polarized, hot stage microscopy), differential scanning calorimeter, thermogravimetric analysis, Fourier transform infrared spectroscopy and powder X-ray diffractometry. The commercial samples of nevirapine had the same polymorphic crystalline form with an anhedral crystal habit. Intrinsic dissolution of nevirapine was similar for both the commercial batches. Powder dissolution showed pH dependency, with maximum dissolution in acidic pH and there was no significant effect of particle size. The samples recrystallized from different solvent systems with varying polarity yielded different crystal habits. Stirring and degrees of supersaturation influenced the size and shape of the crystals. The recrystallized samples did not produce any new polymorphic form, but weak solvates with varying crystal habit were produced. Recrystallized samples showed differences in the x-ray diffractograms. However, all the samples had the same internal crystal lattice as revealed from their similar melting points and heat of fusion. The intrinsic dissolution rate of recrystallized samples was lower than the commercial sample. It was found that the compression pressure resulted in desolvation and partial conversion of the crystal form. After compression, the recrystallized samples showed similar x-ray diffractograms to the commercial sample. Amorphous form showed slightly higher aqueous solubility than the commercial crystalline form.     

Spectral characterization of fluconazole

Reference ¹H, ¹⁹F and ¹³C NMR, mass, IR and Raman spectra are provided to the open literature for the first time for the potent antifungal agent fluconazole, α-(2,4-difluorophenyl)-α-(1H-1,2,4-triazol-1-ylmethyl)-1H-1,2,4-triazole-1-ethanol. The ¹H, ¹⁹F and ¹³C NMR spectra were analyzed in detail to attribute shifts, including ¹⁹F chemical shifts and C-F and F-F coupling constants. The EI mass spectrum, although rich in fragment ions, lacked a molecular ion. FAB and MS/MS experiments were undertaken in support of the structure in order to validate the EI spectrum as a reference mass spectrum. IR and Raman spectra are compared to show the complementary nature of their features and discussed in terms of principal group vibrations. NMR and vibrational data together with assignments are summarized in tabulated form for convenience of use. All these data are consistent with the structure of fluconazole.     

Solid-state characterization of fluconazole

Two polymorphs and three solvates of fluconazole were isolated and characterized by x-ray powder diffractometry, IR spectroscopy, differential scanning calorimetry (DSC), thermogravimetry, and their dissolution rates. The different forms were prepared by crystallization of the original powder in different solvents at different cooling rates. X-ray diffraction patterns of the five solid modifications exhibited substantial differences in both the intensity and position of the peaks. FTIR spectra of the five different solid-state modifications also exhibited differences in the peaks' positions and intensities. DSC thermogram of anhydrate form I showed a single melting point at 139.2 degrees C. Anhydrate form II showed two endothermic peaks at 136.5 and 139.2 degrees C and one exothermic peak in between. The DSC thermogram of acetone 1/4 solvate exhibited two endothermic peaks at 75.5 and 139.2 degrees C. Benzene 1/7 solvate exhibited two endothermic peaks at 131.5 and 138.8 degrees C. Hydrate E exhibited two endothermic peaks at 102.7 and 139.2 degrees C. The DSC thermogram of anhydrate form II showed that this form is sensitive to the application of a mechanical force. The solubility study showed that anhydrate form II and acetone 1/4 solvate have higher solubilities than anhydrate form I while benzene 1/7 solvate and monohydrate have lower solubilities than anhydrate form I. The intrinsic dissolution study confirmed these results.     

Clinical characterization of imuthiol

Imuthiol is a nontoxic agent recruting and regulating T cells. Phase III studies in chronic bronchitis and bronchiectasis showed that immune functions were restored to normal, or near normal values. Cure was obtained in rheumatoid arthritis, tuberculosis and chronic infections in the elderly. Imuthiol is an effective agent for the treatment of syndromes and disease states where the underlying defect is a T-cell deficiency or dysfunction.     

Chromatographic characterization of neurotoxic esterase

Neurotoxic esterase (neuropathy target enzyme, NTE) is an enzyme whose irreversible inhibition is the apparent first step in the induction of organophosphorus-induced delayed neuropathy. NTE is an integral membrane protein and thus must be solubilized before isolation can be attempted. This study describes solubilization of active chicken brain NTE with the nondenaturing detergent 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS) and characterization of the detergent-solubilized enzyme by gel exclusion chromatography. When detergent-solubilized membranes were chromatographed on Sepharose gel exclusion media, NTE activity eluted with an apparent molecular weight of 880-970 kD. When [3H]diisopropylphosphorofluoridate-radiolabeled membranes and unlabeled microsomal membranes were CHAPS-solubilized, combined and chromatographed on Sepharose 4B, NTE activity coeluted with two radiolabeled proteins (Mr = 148 kD and Mr = 112 kD using sodium dodecyl sulfate-polyacrylamide gel electrophoresis with reducing conditions). Another radiolabeled protein (Mr = 92 kD) coeluted exclusively with inhibitor-resistant esterase activity. This study provides strong evidence that the 148 and 112 kD proteins are subunits of a multicomponent NTE complex.     

Toxicological characterization of calcium ketopantoylaminobutyrate

The investigation of toxicity of calcium ketopantoylaminobutyrate (Ca-KPAB) showed that this newly synthesized compound belongs to the class of low-toxicity substances. The LD 50 of Ca-KPAB for oral administration is lower than that of pantogam. No toxicity manifestations and local irritant activity was observed upon chronic administration of Ca-KPAB. The therapeutic index of Ca-KPAB is more than 17 times that of pantogam.     

诺蒎酸的结构表征

目的:采用现代分析技术表征诺蒎酸的结构。方法:由β-蒎烯氧化制备诺蒎酸,在合成和精制的基础上,获得诺蒎酸纯品;采用红外光谱、质谱、核磁共振波谱表征诺蒎酸的结构。结果:采用红外光谱、质谱1、H、13C及二维核磁共振技术对其谱图进行了解析,证实了诺蒎酸的结构,用H-H COSY、C-H COSY等技术完成了1H和13C NMR谱带的归属。结论:诺蒎酸的结构得到了表征,首次给出了该化合物的化学位移。     

Solid-state characterization of mefenamic acid

The purpose of this study was to characterize mefenamic acid (MA) from commercial samples and samples crystallized from different solvents. Various techniques used for characterization included microscopy (hot stage microscopy, scanning electron microscopy), intrinsic dissolution rate, differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy and powder X-ray diffractometry (pXRD). The commercial samples varied in their crystal habit, thermal behavior, and intrinsic dissolution rate. It was found that the commercial samples were polymorphic Form I, which converted to Form II on heating in a DSC pan. Similarly, compression in an intrinsic dissolution rate (IDR) press resulted in the conversion of Form I to Form II. On the other hand, the samples recrystallized from different solvents under varying conditions yielded different crystal habits. Stirring and degree of supersaturation significantly influenced the crystal habit in all the solvents used in the study. Samples crystallized from ethanol and tetrahydrofuran yielded Form I, which behaved similarly to the commercial samples (M1 and M3). Recrystallization from ethyl acetate at a fast cooling rate yielded Form I, which on melting crystallized to Form II. The form I crystallized from ethyl acetate by fast cooling converted partially to form II on storing at ambient conditions. Forms I and II of MA were enantiotropically related. The results demonstrate the variable material characteristics of the commercial samples of MA and the influence of the crystallizing conditions on the formation of the polymorphs.     

Kinetic characterization of alkaline mesentericopeptidase

Comparative studies of the hydrolysis of succinyl-Ala₂-Phe-methylcoumarylamide with mesentericopeptidase, a mesophilic extracellular serine proteinase from Bacillus mesentericus, and proteinases produced by organisms representing different levels of evolutionary development, were performed. Drastic differences in the proteolytic coefficient k_cat/K_m, were found. As regards their catalytic efficiency, the proteinases studied can be placed in the following order: mesentericopeptidase < subtilisin Novo ? subtilisin DY < proteinase K < subtilisin Carlsberg < thermitase < α-chymotrypsin. The size of the substrate-binding site of mesentericopeptidase for synthetic peptides was studied by using chloromethyl ketones with the general formula benzyloxycarbonyl-Ala-Phe-CH₂Cl (n= 1, 2, 3). The presence of at least five binding subsites (S₁… S₅) on the S-side of the hydrolysed bond was suggested. Studies of the primary specificity of mesentericopeptidase with a series of dipeptide chloromethyl ketones having the general formula benzyloxycarbonyl-Ala-Aa-CH₂Cl (Aa = Ala, Val, Leu, Phe) revealed the following order of reactivity toward these inhibitors: Aa = Leu ? Ala > Phe > Val. Kinetically, mesentericopeptidase is similar to subtilisin BPN′/Novo.     

Subunit characterization of NMDA receptors

NMDA receptors are a subclass of excitatory, ionotropic L-glutamate neurotransmitter receptors. They are.heteromeric, integral membrane proteins being formed by the assembly of the obligatory NR1 subunit together with modulatory NR2 subunits of which four different types, NR2A-NR2D, have been described. This results in a heterogenous population of receptor proteins with distinct pharmacological and biophysical properties thus yielding potential for the development of NMDA receptor subtype-selective therapeutic agents. Anti-NMDA receptor subunit antibodies have been generated and used in immunoprecipitation or immunoaffinity purification studies to determine the in vivo subunit complements of NMDA receptors. This article summarizes knowledge on the subunit compositions of NMDA receptors based on these approaches together with the current status of NMDA receptor subunit stoichiometry and hence quaternary structure. of native NMDA receptors.     

青霉素酶分离纯化及酶学性质研究

本文对蜡状芽孢杆菌CMCC(B)63301产青霉素酶的分离纯化工艺及酶学性质进行了研究。粗酶液通过硫酸铵分级盐析、超滤除盐浓缩、SephadexG-75凝胶层析纯化后得到的青霉素酶液的比活力为68.2×106u/mg,纯化倍数为11.32,酶活回收率为35.04%。经SDS-PAGE检测为单一区带。该酶作用的最适温度为37℃,最适作用pH范围为6.5～7.0,在0～20℃下存放比较稳定。酶液中添加5%NaCl或5%甘油可提高酶的保存稳定性。     

N-叔丁基-α-苯基硝酮的合成及表征

目的研究优化N-叔丁基-α-苯基硝酮的合成方法。方法采用羰基化合物与胺脱水的方法,以苯甲醛,叔丁胺、氯过氧苯甲酸等为原料合成目标产物N-叔丁基-α-苯基硝酮(TM),通过熔点测定、核磁及质谱分析表征其化学结构,研究了不同溶剂、不同原料、不同反应摩尔比对转化率和纯度的影响。结果获得最优化的合成路线和处理方法,产物结构鉴定与N-叔丁基-α-苯基硝酮(TM)一致,纯度大于98%。结论采用此种合成方法成本低、纯度高,经济可行。     

Physicochemical characterization of protamine-phosphorothioate nanoparticles

Protamine-oligonucleotide nanoparticles represent effective colloidal drug carriers for antisense phosphorothioate oligonucleotides (PTO). This study describes improvements in particle preparation and the physicochemical properties of the complexes prepared. The influence of component concentrations, length of the PTO chain and the PTO/protamine weight ratio on particle formation and size, shape and surface charge of the particles were studied in detail. Nanoparticles with diameters of 90–200?nm were obtained, using protamine free base (PFB) and phosphorothioate in water. The chemical composition of the nanoparticles was analysed. More than 90% of the PTO could be assembled in the particle matrix using a ≥1?:?2 ratio (w/w) of PTO and PFB. About 53–68% of the PFB was incorporated in the particle matrix. The complexes had a zetapotential of ?19 up to +32?mV, depending on the PTO/PFB ratio. The kinetics of the assembly of this binary system were observed by dynamic light scattering (DLS) measurements and by sedimentation velocity analysis in the analytical ultracentrifuge (AUC). In addition, scanning electron microscopy (SEM) and atomic force microscopy (AFM) were applied to verify the results of DLS and the ultracentrifuge measurements. According to sedimentation velocity analysis, the particles were only moderately stable in water and unstable in salt solutions. However, the colloidal solution in water could be stabilized by polyethylenglycol 20?000 (PEG), which also led to an increase of stability in cell medium.     

Synthesis and characterization of iodoazidobenzylpindolol

A high affinity beta-adrenergic ligand, iodoazidobenzylpindolol, was synthesized and characterized. The absorption spectrum of this compound changed markedly upon photolysis, consistent with decomposition of the azide group. This compound has a KD of 5--7 x 10(-10) M for the duck erythrocyte ghost beta-adrenergic receptor when measured in a competitive binding assay.